The present invention relates to chain wear monitoring devices. Such devices are designed to determine the extent of wear on a chain while it is moving. Such devices are used for example to monitor wear on moving chains used in overhead conveyors. Such chains wear at the junction between the links of the chain, and often occur at the pins which are used to join adjacent links of the chain.
Often, such devices use one or more light beams or laser beams which are broken by passing measuring points on the chain. By using a first measuring point on one chain link, and a second another measuring point on a following chain link, one can use various different algorithms to determine the wear occurring between those measuring points. In U.S. Pat. No. 6,993,978, entitled Pin Detection System, pins or like projections, which project from the top of link pins in the chain, are provided as measuring points. One advantage to the use of such pins is that there are no intervening irrelevant light blocking items at which a light or laser beam might be broken. For example, some chains use guide rollers which extend across the opening between side links, and interfere with using the leading edge of successive center links as measuring points. In such a chain, the beam is broken not only by the leading edge of the center link, but by the guide roller located between successive center links.